Greece: Adverse weather forecast across much of the country through at least Jan. 12 /update 1

Event

Thunderstorms bringing heavy rainfall, and strong winds, are forecast across much of Greece through at least Jan. 12; heavy snowfall in some mountainous areas is also predicted. Authorities have updated weather warnings on Jan. 10 to include the highest warning level.

The Hellenic National Meteorological Service has warned that a storm system will bring heavy rain and thunderstorms to the Docadenese Islands, eastern Aegean Islands, Crete, and coastal parts of central and eastern Macedonia regions throughout Jan. 10, and to the central and southern Ionian Islands, Peloponnese, eastern Sterea, and Thessaly regions late Jan. 10. Heavy rains are forecast in the Sporades Islands, northern Evia, Thessaly, southern parts of central Macedonia, and eastern Sterea regions on Jan. 11. The storm is expected to continue to bring heavy rain to the Dodecanese Islands, Cyclades Islands, and Crete throughout Jan. 12 and to the Sporades Islands, Evia, and Thessaly early Jan. 12. Very strong winds are forecast in the northern Aegean Islands Jan. 11-12. The storm is also forecast to bring heavy snowfall to mountainous areas of Thessaly and western and central Macedonia late Jan. 10. Snowfall is forecast to reach lower elevations Jan. 11 in Macedonia, Thessaly, central and eastern Sterea, and Thrace regions. Snowfall is expected to continue in these areas and Evia, Jan. 12.

As of Jan. 10, authorities have issued the following warnings:

Red snow or ice warning: Thessaly Region.
Red heavy rain warnings: Thessaly and eastern Sterea and Evia regions.
Red thunderstorm warning: Dodecanese Islands.
Orange snow or ice warnings: eastern Serea and Evia and western Peloponnese regions.
Orange thunderstorm warnings: western Peloponnese Region, Crete, North East Agean Islands, and Ionian Islands.
Orange heavy rain warning: Attica Region.
Yellow thunderstorm warnings: eastern Sterea and Evia, central Macedonia, Thessaly, and eastern Peloponnese regions, as well as Crete and the Cyclades Islands.

Authorities will likely issue new alerts or update/rescind existing advisories as weather conditions change over the coming days.

Hazardous Conditions
The storms could produce rounds of heavy rainfall, strong winds, and isolated thunderstorm activity across the affected area. Sustained heavy rainfall could trigger flooding in low-lying communities near rivers, streams, and creeks. Urban flooding is also possible in developed areas with easily overwhelmed stormwater drainage systems. Sites located downstream from large reservoirs or rivers may be subject to flash flooding after relatively short periods of intense rainfall. Landslides are possible in hilly or mountainous areas, especially where heavy rainfall has saturated the soil. Power outages could occur throughout the affected area.

Precipitation could fall as snow in the higher elevations over the coming days. Wind gusts could cause blowing and drifting snow; decreased visibility is likely in mountainous areas. There is the possibility of avalanches in mountainous areas where the snowpack has become unstable due to heavy snowfall.

Transport
Floodwaters and related debris may render some bridges, rail networks, or roadways impassable, impacting overland travel in and around the affected area. Flooding in urban areas could also result in significant traffic congestion. Heavy snow will likely make driving hazardous in some areas; authorities could implement temporary road closures or detours in such locations. Mountain passes and tunnels could be closed as a precautionary measure during periods of intense snowfall.

The disruptive weather will possibly cause some delays and cancellations at regional airports. Authorities may temporarily suspend port operations if strong winds trigger hazardous sea conditions, impacting freight and passenger maritime traffic. Flooding or snow could block regional rail lines; freight and passenger train delays and cancellations are possible in areas that see heavy rainfall and potential track blockages.

Disruptions triggered by inclement weather and resultant hazards, such as flooding or avalanches, could persist well after conditions have improved - it could take days before any floodwaters recede and/or officials clear debris. If there is severe damage to infrastructure, repair or reconstruction efforts may result in residual disruptions.

Advice

Monitor local media for weather-related updates and advisories. Confirm all transport reservations. Stay away from elevated streams, creeks, and other watercourses that are prone to flash flooding. Do not attempt to navigate flooded roadways. Exercise caution in elevated terrain due to the threat of landslides. Charge battery-powered devices in the case of prolonged electricity outages.